Field of Endeavor
The present invention relates to devices, systems, and processes useful as injection syringes, and more specifically to syringes useful for making retrobulbar injections.
Brief Description of the Related Art
Many ophthalmology procedures are performed with a local anesthetic and intravenous sedation. Retrobulbar or peribulbar (behind the eye or adjacent to the eye) injections of local anesthetic are often used for intraocular surgeries, such as cataract extraction, retinal, vitreous, corneal, and pterygium surgeries. Retrobulbar injections are typically performed by placing a 1½ or 1¼ inch needle through the lateral lower lid adjacent to the inferior orbital rim and pushing deep into the orbit. In some cases the needle may be directed superomedially when it is deep in the orbit. This movement is to permit better flow of local anesthetic into the orbital apex. The local anesthetic is injected after the needle is in place. The needle is then withdrawn. The purpose of the local anesthetic is to provide anesthesia and akinesia (prevent movements of the eye which is critical during delicate intraocular surgery).
Peribulbar injections of local anesthetic involve placing the needle through the lateral lower lid adjacent to inferior orbital rim. However, the needle is not pushed as deep into the orbit as with a retrobulbar injection.
During these procedures, the surgeon cannot visualize the needle or orbital structures with this technique; that is, the needle is placed blindly. Therefore, vital structures such as the optic nerve, blood vessels, and the eye cannot be avoided.
Many complications can occur during retrobulbar, and to a lesser extent peribulbar, injections of local anesthetic. A retrobulbar hemorrhage can occur if the needle encounters a blood vessel. A severe retrobulbar hemorrhage can place pressure on the optic nerve and cause blindness. The needle can also puncture the eye which may result in severe visual loss. The needle can also penetrate the optic nerve sheath. The injection of a commonly used anesthetic, bupivicaine, causes respiratory arrest in these cases.
An effort to avoid these complications has been the use of anesthetic eyedrops alone for cataract extractions. This technique is not possible in patients who are not cooperative and are too anxious. The use of anesthetic eyedrops alone is not possible for long surgeries such as retinal or vitreous surgeries. Retrobulbar anesthesia is still needed for patients who are anxious, unable to cooperate, or for retinal or vitreous surgeries, or corneal transplants.
An effort to reduce the complications of retrobulbar anesthetic injections is shown with the metal Atkinson retrobulbar needle. This needle is somewhat more rounded at the tip than typical needles used for local anesthetic injections. However, the needle is still sharp and metallic and can cause all of the complications listed above.
Another problem is that the injection is out the distal end of the needle only. The surgeon must angle the needle toward the optic nerve to make the anesthetic flow toward the orbital apex. This maneuver increases the rate of complications described above.
Needles are also used during other types of surgery for the injection of local anesthetic. In many procedures, the same syringe and needle are used repeatedly. That is because the local anesthetic effect may dissipate during the procedure, or the surgery may extend to more areas that were not anesthetized by the original injections. In other cases, areas of bleeding require additional injections to allow the epinephrine in the local anesthetic to constrict the blood vessels and stop the bleeding.
The same needle and syringe are used repeatedly because of the added time (and cost) to obtain a new needle for each of many injections. The cap must be placed on the needle between uses. The needle and syringe must be picked up, placed on a tray, handed from the surgical technician to the surgeon and vice versa, and otherwise handled. All of these maneuvers place the operating personnel at a risk for an accidental needle stick and the transmission of disease such as HIV and hepatitis C.
There are various safety needles for injections and the placement of intravenous lines available. However, all of these needles and intravenous needles/lines are for a single use only.
U.S. patent application Ser. No. 12/496,431, filed 1 Jul. 2009, and published as U.S. Patent Application No. 2010/0010468 A1, by Bruce Becker (“'431 application”), the inventor herein, describes several useful and innovative needles and syringes, which is incorporated by reference herein.